1. Field of the Invention
The present invention relates to the field of steering systems for land vehicles. More particularly, the present invention relates to steering systems wherein the steerable wheels are selectively movable inboard and outboard of the vehicle frame, and wherein the distance between the steerable wheels is selectively adjustable.
2. Background
Most all land vehicles include steerable wheels which are rotatable about a generally vertical steering axis, typically generally perpendicular to the wheels axis of rotation, for turning the wheels and thereby directing the vehicle in a desired direction. In this regard, many steering systems have been devised and are currently in use. For example, the steerable wheels can be mounted to wheel ends such as driven wheel motors and non-driven stub axles or spindles which are pivotally supported on a yoke with a king pin. By rotating the wheel ends about the king pin/steering axis, the steerable wheels can be turned for directing the vehicle as desired. Of course, in vehicles having a pair of spaced apart steerable wheels, one on each of the left and right sides of the vehicle, the left and right wheel ends are simultaneously turned in the desired direction.
In most vehicles, the steerable wheels are fixed relative to the vehicle frame or chassis. That is, the steerable wheels cannot be moved inboard or outboard and the distance between the left and right steerable wheels is fixed.
It is oftentimes desirable to adjust the steerable wheels inboard/outboard position and/or the distance between the left and right steerable wheels. For example, in construction and off road vehicles, it may be desirable to sometimes increase the distance between the steerable wheels and thereby increase the stability of the vehicle. In agricultural vehicles such as combines and chemical spraying vehicles, it may be desirable to adjust the steerable wheels inboard/outboard location and/or the distance between the left and right steerable wheels so as to place the wheels between the crop rows.
Although steering apparatus have been devised for adjusting the distance between the left and right steerable wheels, a need exists for an improved steering system capable of adjusting the steerable wheels inboard/outboard locations and/or the distance between the left and right steerable wheels.